If you draw circles around the Earth horizontally, the circles at the top and the bottom are going to have a smaller radius. But there are still the same number of meridians passing through each and...
It's like an X and Y axis; Longitude goes up and down, like the Y axis, and Latitude goes around the earth, like an X axis. You may want to find a picture to further see this.
No. At the equator each degree of longitude is about 70 miles apart. As you go north or south towards the poles, they get closer and closer until they meet at the poles.